The assembly of nanoparticles with controllable sizes, shapes, and interparticle properties is essential to the exploitation of the unique electronic, optical, magnetic, and chemical properties of the nanoscale materials. A challenging area in the exploitation of the optical properties of the dye-nanoparticle combination as spectroscopic probes, photochemical or sensory devices is the ability of controlling the inter-particle interactions and reactivities. In recent years, the coupling of molecularly-capped nanocrystals to molecular mediation has attracted increasing interest in developing such abilities. The capping/mediator molecules act as a protective shell, resisting the propensity of aggregation, and can also be tailored to define the interfacial spacing and chemistry in controllable ways. Many examples that exploit such nanostructured interfacial properties have recently emerged, including ligand-exchange reaction (see Hostetler, M. J., et al., J. Am. Chem. Soc. 118: 4212 (1996); Hostetler, M. J., et al., Langmuir 15: 3782 (1999); Templeton, A. C., et al., J. Am. Chem. Soc. 120: 1906 (1998); Templeton, A. C., et al., J. Am. Chem. Soc. 120: 4845 (1998)), layer-by-layer stepwise assembly (see Musick, M. D., et al., Langmuir 15: 844 (1999); Zamborini, F. P., et al., J. Am. Chem. Soc. 122: 4514 (2000); Templeton, A. C., et al., Langmuir 16: 6682 (2000)), DNA-linked assembly (see Mirkin, C. A., et al., Nature 382: 607 (1996); Elghanian, R., et al., Science 277: 1078 (1997); Taton, T. A., et al., J. Am. Chem. Soc. 122: 6305 (2000)), polymer- or dendrimer-mediated molecular recognition (see Boal, A. K., et al., Nature 404: 746 (2000); Boal, A. K., et al., J. Am. Chem. Soc. 124: 5019 (2002); Frankamp, B. L., et al., J. Am. Chem. Soc. 124: 15146 (2002); Srivastava, S., et al., Chem. Mater. 17: 487 (2005); Kariuki, N. N., et al., Langmuir 18: 8255 (2002)), molecularly-mediated exchange-crosslinking (see Leibowitz, F. L., et al., Anal, Chem. 71: 5076 (1999); Zheng, W. X., et al., Anal, Chem. 72: 2190 (2000); Han, L., et al., Chem. Mater. 15: 29 (2003)), and multidentate thioether-mediated assembly (see Maye, M. M., et al., J. Phys. Chem. B 109: 2578 (2005)). Emerging applications of the molecularly-mediated assemblies of nanoparticles include chemical sensing (see Zheng, W. X., et al., Anal. Chem. 72: 2190 (2000); Han, L., et al., Anal. Chem. 73: 4441 (2001); Zamborini, F. P., et al., J. Am. Chem. Soc. 124: 8958 (2002); Leopold, M. C., et al., Faraday Discuss. 125: 63 (2004); Israel, L. B., et al., J. Electroanal. Chem. 517: 69 (2001)), catalysis (see Narayanan, R., et al., J. Am. Chem. Soc. 126: 7194 (2004); Zhong, C. J., et al., in Nanotechnology in Catalysis, Zhou, B., et al., Eds.; Kluwer Academic/Plenum Publishers: New York, Vol. 1, Chapter 11, pp 222-248 (2004); Zhong, C. J., et al., Adv. Mater. 13: 1507 (2001)), drug delivery, nanoelectronics (see Musick, M. D., et al., Langmuir 15: 844 (1999); Chen, S. Langmuir 17: 6664 (2001); Chen, S., J. Am. Chem. Soc, 122: 7420 (2000); Chen, S., et al., Am. Chem. Soc. 124: 5280 (2002); Hicks, J. F., et al., J. Am. Chem. Soc. 123: 7048 (2001)), and medical diagnostics (see Mirkin, C. A., et al., Nature 382: 607 (1996); Elghanian, R., et al., Science 277: 1078 (1997); Taton, T. A., et al., J. Am. Chem. Soc. 122: 6305 (2000); Zheng, W. X., et al., Analyst 125: 17 (2000)). The immobilization of dye molecules onto nanoparticles has on the other hand attracted recent interest in exploiting the optical properties for applications in chemical and biological systems. For example, the fluorescence quenching of small dye molecules has been studied using gold nanoparticles of different sizes (see Huang, T., et al., Langmuir 18: 7077 (2002); Ghosh, S. K., et al., Chem. Phys. Lett. 395: 366 (2004)). It is revealed that complementary oligonucleotides lead to the quenching phenomenon for single stranded DNA linked-metal nanoparticles (see Li, H., et al., J. Am. Chem. Soc. 126: 10958 (2004); Li, H., et al., Anal. Chem. 76: 5414 (2004)), which eliminates target labeling. DNA hybridization assay has been demonstrated using bar-coded metal nanowires with selected fluorophores that have wavelength-dependent reflectivities (see Nicewarner-Pena, S. R., et al., Science 294: 137 (2001); Nicewarner-Pena, S. R., et al., J. Phys. Chem., B 107: 7360 (2003)). Oligonucleotides that contains single base mismatch are recently shown to be effectively distinguished based on the quenching properties of gold nanoparticles on fluorescence dyes (see Maxwell, D. J., et al., J. Am. Chem. Soc. 124: 9606 (2002)). The use of fluorescent dye-doped nanoparticles for bioanalytical detection has shown to be useful in medical diagnostics and labeling (see Lian, W., et al., Anal. Biochem. 334: 135 (2004)). The study of dye-capped metal nanoparticles has also attracted interest in the basic research (see Thomas, K. G., et al., Acc. Chem. Res. 36: 888 (2003); Chandrasekharan, N., et al., J. Phys. Chem. B 104; 11103 (2000); Barazzouk, S., et al., J. Phys. Chem. B 109: 716 (2005); Nasr, C. P., et al., J. Phys. Chew. 100: 11054 (1996); Cu, T., et al., Chem. Mater. 15: 1358 (2003); Hranisavljevic, J., et al., J. Am. Chem. Soc. 124: 4536 (2002); Wang, G. L., et al., Anal. Chem. 74: 4320 (2002); Huang, T., et al., J. Phys. Chem. B 105: 12498 (2001); Templeton, A. C., et al., J. Am. Chem. Soc, 121: 7081 (1999); Dulkeith, E., et al., Nano Lett., 5: 585 (2005)). In the study of the fluorescence quenching as a result of the proximity of dye molecules to the metal nanoparticle surface, important insights have been gained into the molecular interactions involving electron or energy transfer between dye and metal particles (see Thomas, K. G., et al., Acc. Chew. Res. 36: 888 (2003)). While the prior studies have shown promising application of dye-nanoparticle combination as spectroscopic probes, relatively little attention has been paid to how the interparticle interactions and reactivities can be utilized for nanostructured assembly.
The present invention is directed to overcoming these deficiencies in the art.